Transmission not shifting. *solved

[nathaninwa]

This was a problem from a faulty relocated pressure switch on my trans brake valve body


Hey guys. Just parked waiting for a trailer! Thought I would post just to get some feedback. Car won't shift out of first gear 90% of the time, regardless of I'm in manual mode or auto mode. When viewing the shift position in microsquirt, it will indicate 4 gear, then drop down to -5. When it stays in 4 it will shift, and will stay in gear when it indicates -5, but if I come to a stop it won't come out of first gear them

There's a red indicater that's says SEL SELECT in red.

I'm hoping this just means that my 4l80e needs a new internal gear selector switch

Any thoughts?

[Raymond_B]

I wish I could help, been working on MLPS issues myself. But I did learn when you get the red sel select then it does not know what gear you're in. Do you have analog or digital range selector (ford calls it an MLPS). If you have analog James let me know that you can set a TS gauge to get RAW AD counts to figure out what voltage the Megasquirt is seeing. Look at my MLPS thread, it might shed some insight, hopefully.

[nathaninwa]

Mines analog. Just DC voltage input from a pressure switch inside the tranny Think copper button actuated by hydraulic pressure. I'm home now and about to swap in the original unit to test

[nathaninwa]

It worked great for about 50 miles last year and about 20 miles this morning. The tranny did come apart some this winter for a main shaft and direct drum upgrades. I wonder off could be a pressure leak, or a wiring deal at the trannys case plug? Tranny fluid is cooling down now and I'll drain in a while and get the pan pulled

[Raymond_B]

It worked great for about 50 miles last year and about 20 miles this morning. The tranny did come apart some this winter for a main shaft and direct drum upgrades. I wonder off could be a pressure leak, or a wiring deal at the trannys case plug? Tranny fluid is cooling down now and I'll drain in a while and get the pan pulled

While it's cooling off you could key it on and set up that ADC gauge in TS, that will tell you what voltage the MS is seeing. Although with no pressure there's no way to really test gear position, so maybe a moot point.

[jsmcortina]

4L80E uses pressure activated ground switches.

James

[nathaninwa]

I looked in the tranny manual and didn't find any specific adc info. I'm able to still start this engine up and test and maybe pinout the problem?

[nathaninwa]

Did some snooping around. In my "why isn't my laptop connecting to the tranny controller moment" I was only able to use one of the tranny pan bolts with the ring connector on the pan itself which may have some coating on it since it's not rusting like around my drain plug. So I moved it to the actuall case and used some compressed air on the tranny plug. Seems to work on the jack stands now, runs through each gear just nicely for about 5 mins

So it's either some dirty wiring or something heat related. I'll test tomorrow after work

[nathaninwa]

So here is what I have found so far
Tranny works fine (except manual mode doesn't seem to work, I need to find an indicator to make sure it's working) till it got to 185*. Then it faulted Stayed stuck in 4th gear till I slowed to turn into my neighborhood then faulted to 1st gear

I'm letting it cool now to verify and will dig out the abc wires and check voltages

Maybe if there is a fault, the tranny should default to 3rd gear, unlocked

[nathaninwa]

Got some data. Did it at 165* now, so maybe not so much temp related

Gear Selector indicated -5. Volt meter grounded. A is 2.1 volts. B is 0 and C is 0. Voltmeter connected to 12v. A is 11.5. B is 13.5. C is 13.5

Moved gear shift to park and indicated -1. Volt meter grounded, A is 2 volts, B is 0, and C is 4.7. Volt meter hooked to positive, A is 11.4, B is 13.5 and C is 8.6

Does this indicate a bad selctor pressure switch inside?

[Raymond_B]

James mentioned it uses a pressure activated ground. Did you do the test with the vehicle running?

I am not very good with electrical troubleshooting, but in my mind it seems you should be checking for an open or closed circuit?

Info here would maybe illustrate better.

http://www.msgpio.com/manuals/mshift/4L80E/4L80e.html

[nathaninwa]

The engine was running. The place I got the rebuild kit from seems to think its the pressure switch. I guess I'm verifying it's the switch versus the microsquirt gone funky

[nathaninwa]

I have the shifter postion switch swapped out. Works as normal on a test fire up. Have a slight injector leak now I need to fixed first then weather permitting tomorrow I'll take it back out and test

[nathaninwa]

Ok guys. I'm at a loss here. Transmission is still not shifting when it gets hot. I have replaced the internal shift postion switch, checked all electrical inside Once it got to 170* today it quit shifting with a SEL selector fault. It was a slow transition as the times before. Cruising in postion 3 it dips to -5 speratically. Then a constant fault. Once speed stops it defaults to gear 1 and won't up shift

I unhooked my tranny brake as it reads -5 when I'm stalling up. No difference

I even loaded the transmission firmware on my I/O microsquirt with the same results

What's happening electrically when it get hot? When it's shifting the car is an animal

I checked for voltages while its freakin out and no changes are indicated. Is there something I can bypass to test or something internally temp related?

[nathaninwa]

my current msq

[nathaninwa]

just took a datalog the last 2 markers are me putting into postion 4 and shortly after it indicates gear -5

Maybe it's worth mentioning. The actual gear postion gauge never indicates I'm in reverse. Stays in gear 1 while in park and reverse

[nathaninwa]

Just an idea here. To separate the transmission from the contller, can I cut the 3 ABC wires when it fails and simply ground the appropriate pins to put it in what gear I need? That internal switch seems a grounding deal, so if I ground like pin A and pin C for 4th, given that's the combo, this should put me in a good gear and let me know if it's tranny or controller?

[jsmcortina]

Or rather than cut them, probe them and check the voltages match up against the selector truth table that's in the manual.

James

[nathaninwa]

I have them exposed at the moment. I'll find the voltage chart and verify cold and hot, but will grounding them in the proper order the correct thing to do in case I'm further away from home than first gear will let me drive?

[nathaninwa]

Ok. I verified in the manual that grounding the needed pins and letting the others float will trick the computer. I don't see a voltage reference tho, just ground or high. I know that the ignition outputs are used for 2 wires and should be around 5v high, but what about the other wire?